Nestled in the San Juan Mountains at 9,300 feet, and surrounded by 13,000-foot peaks, Silverton, Colo., seems an unlikely place for a dust storm, especially with two feet of snow on the ground. So Chris Landry was alarmed on the afternoon of April 3 when he spotted a brown haze on the horizon; an hour later, a howling wind had engulfed the town in a full-fledged dust storm, turning everything from the sky to the snow a rusty red.

"It was almost surreal," recalled Landry, executive director of the Center for Snow and Avalanche Studies. The landscape looked like Mars after the storm passed, he said: "You could feel the dust, you could taste the dust."

The scene Landry witnessed that day was the most severe example of a phenomenon that has overtaken parts of the West this year, one that could exacerbate a slew of environmental problems there in the years to come. The Colorado Rockies, including the headwaters of the Colorado River and the Rio Grande, have experienced 11 serious dust storms this year, a record for the six years researchers have been tracking them.

More important, an increasing amount of airborne dust is blanketing the region, affecting how fast the snowpack melts, when local plants bloom and what quality of air residents are breathing.

The dust storms are a harbinger of a broader phenomenon, researchers say, as global warming translates into less precipitation and a population boom intensifies the activities that are disturbing the dust in the first place. Jayne Belnap, a research ecologist at the U.S. Geological Survey who has studied the issue, predicts that by midcentury, the fragility of the region's soil "will be equal to that of the Dust Bowl days."

"We're headed for this massive soil movement, these massive dust storms on a frequency we're not used to, and it's going to have enormous ecosystem impacts," Belnap said. "No one has an appreciation for the scope of the calamitous impacts."

Dust storms are not new in the West, but the fact that so much dust is on the move reflects that across vast areas, soil is being loosened by off-road vehicles, livestock grazing, and road development for oil and gas production, much of it on public land. A Washington Post analysis of federal data from areas managed by the Bureau of Land Management found that between 2004 and 2008, off-road vehicle use rose 19 percent, the number of oil and gas wells increased 24 percent and grazing acreage climbed 7 percent.

The trends have sparked an intense debate between interests being blamed for loosening the soil and those calling for controls on those activities.

Advocates for off-road vehicle users, for example, charge that environmentalists have seized upon the dust issue as a political club in their efforts to curb the increasingly popular recreational sport.

"A lot of the public land in the West is a very dusty place. What human uses make it more dusty, and to what extent, is unknown," said Brian Hawthorne, public lands policy director for the BlueRibbon Coalition, which represents off-road enthusiasts. "There's just no studies on it."

Scientists are trying to get better measurements of how much soil is getting stirred up -- and the consequences.

People tend to think of arid regions as inherently dusty, but research by the U.S. Geological Survey and others has shown that even dry soil, if undisturbed, stabilizes plant life and can provide a critical, albeit fragile, crust.